In a voice communication device such as a cellular phone or a telephone conference system, it is very important to reduce noise. Many voice communication devices, such as cellular phones, employ a technique for removing background noise (ambient noise). For example, patent literatures 1 and 2 disclose background arts for removing background noise from an input signal containing a voice signal and background noise.
Patent literature 1 discloses a noise eliminating technique, to eliminate background noise without deteriorating sound quality, of eliminating estimated background noise obtained by eliminating a sharp change component of background noise from an input signal and eliminating re-updated estimated background noise including the sharp change component of the background noise in a frequency band having low S/N ratio. Patent literature 2 discloses a technique, in a background noise eliminating device, for eliminating background noise from a signal containing a voice signal and background noise, of determining whether a present frame signal is in a voice interval or a noise interval on the basis of an S/N ratio for each band calculated on the basis of the bandwidth spectrum in a past noise interval.    Patent Literature 1: Japanese Unexamined Patent Application Publication No. H10-171497    Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2001-265367